Connector device including planar member with slits to receive electrical tabs of fuel cell stack

ABSTRACT

An electrical connection system for cell voltage monitoring in a fuel cell stack. A fuel cell stack assembly comprises a plurality of fuel cells disposed in a stacked configuration, each cell substantially parallel to an x-y plane and including an electrical tab extending laterally from an edge of a plate in the cell in the x-direction to form an array of tabs extending along a side face of the fuel cell stack in a z-direction orthogonal to the x-y plane. A connector device comprises a planar member having a plurality of spaced-apart slits formed in an edge of the planar member, each slit having an electrically conductive material on an inside face of the slit. The slits are spaced along the edge of the planar member and configured to receive the tabs by sliding engagement in the y-direction. Alternatively, each tab may be crimped to create a distortion in the tab out of the x-y plane of the plate and a connector device comprises a planar member having a plurality of generally parallel slits formed in the body of the planar member, each slit having an electrically conductive material on an inside face of the slit, the slits being spaced within the planar member and configured to receive the tabs by sliding engagement in the x-direction so that each tab engages with at least a portion of the electrically conductive material on the inside face of a respective slit.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/989,379 filed Nov. 12, 2013, which is a National Stage ofInternational Patent Application No. PCT/GB2011/052265 filed Nov. 18,2011, which claims priority to Great Britain patent application no.1020478.2 filed Dec. 3, 2010, the contents of which are incorporated intheir entirety as if fully set forth herein.

FIELD

The disclosure to electrical connector systems used in fuel cell stacksto make electrical connections to a plurality of individual cells withina fuel cell stack.

GENERAL BACKGROUND

Conventional electrochemical fuel cells convert fuel and oxidant intoelectrical energy and a reaction product. A typical fuel cell comprisesa membrane-electrode assembly (MEA) sandwiched between an anode flowfield plate and a cathode flow field plate. The flow field platestypically include one or more channels extending over the surface of theplate adjacent to the MEA for delivery of fluid fuel or oxidant to theactive surface of the MEA. The flow field plates also perform thefunction of providing an electrical contact to the MEA across thesurface thereof. In a conventional fuel cell stack, a plurality of cellsare stacked together, so that the anode flow field plate of one cell isadjacent to the cathode flow field plate of the next cell in the stack,and so on. In some arrangements, bipolar flow plates are used so that asingle flow field plate has fluid flow channels in both sides of theplate. One side of the bipolar plate serves as an anode flow plate for afirst cell and the other side of the flow plate serves as a cathode flowplate for the adjacent cell. Power can be extracted from the stack byelectrical connections made to the first and last flow plate in thestack. A typical stack may comprise many tens or even hundreds of cells.

In many fuel cell stacks, it is important to be able monitor the voltageof individual cells in the stack. Thus, it is necessary to provideelectrical connector tabs to many of the flow plates in the stack. Thesecell voltage monitoring tabs extend, in the planes of the plates,laterally outward from the stack thereby forming an array of tabs alongan edge face of the stack, so that individual electrical connectors maybe coupled to each tab.

DESCRIPTION

In an effort to reduce the size and weight of fuel cell stacks, and thusincrease the power density of a fuel cell stack, there has been a trendtowards ever thinner flow plates, which may be formed from thin sheetsof electrically conductive metal or foil that are corrugated to form therequisite channels in each face of the flow plate. This cansubstantially reduce size and weight of the fuel cell stack, but createsa potential difficulty in the formation of cell voltage monitoring tabsextending laterally from edges of the flow plates. A typical thicknessof flow plates has hitherto been reduced to approximately 0.6 mm, whichcauses few problems and individual cell voltage monitoring connectorshave been used. However, proposals for further reductions in flow platethickness, for example down to 0.1 mm, can cause significantdifficulties for conventional electrical connectors.

The decreasing thickness of the flow plates means that the individualtabs extending therefrom may no longer have the requisite stiffness orstructural integrity to resist the necessary compressive force assertedby a conventional push-fit spring-loaded or friction-fit femaleconnector which is applied to each tab from the ends of the tabs distalto the fuel cell stack.

Another problem is that the tabs generally do not form a perfect arrayin which every tab is fully aligned with, and equally spaced from, theadjacent tabs. This is due to normal manufacturing and assemblytolerances when assembling the fuel cell stack and this can provide anadditional difficulty in aligning the tabs if it is desired to use amulti-tab connector.

Aspects of exemplary implementations herein disclose devices, systemsand methods to address these and other problems.

In an exemplar there is disclosed aspects of a fuel cell stack assemblycomprising: a plurality of fuel cells disposed in a stackedconfiguration, each cell substantially parallel to an x-y plane andincluding an electrical tab extending laterally from an edge of a platein the cell in the x-direction to form an array of tabs extending alonga side face of the fuel cell stack in a z-direction orthogonal to thex-y plane; a connector device comprising a planar member having aplurality of spaced-apart slits formed in an edge of the planar member,each slit having an electrically conductive material on an inside faceof the slit; and the slits being spaced along the edge of the planarmember and configured to receive the tabs by sliding engagement in they-direction.

Each slit preferably has a curved profile along its length. The slits ofthe connector may have a profile in the form of an ‘S’-shape along thelongitudinal direction. Each slit of the connector may have a curvedprofile along its depth. The slits may be parallel to one another. Atleast some tabs may have a hook at the distal end of the tab, each hookextending in the y-direction, each hook configured to extend over aclosed end of a respective slit of the planar member. Each slit mayinclude at least one guide taper in the planar member at the open end ofthe slit. The array of tabs may comprise two rows of tabs separated inthe y-direction, the second row being offset from the first row in thez-direction so as to facilitate electrical connection to a different setof plates in the stack than the first row. The planar member may be aprinted circuit board with electrically conductive tracks extendingacross the planar surface to the electrically conductive material on theinside face of each slit. At least one slit may include a retentionmember configured to inhibit release of tabs from the connector in they-direction.

In an exemplar there is disclosed aspects of a fuel cell stack assemblycomprising: a plurality of fuel cells disposed in a stackedconfiguration, each cell substantially parallel to an x-y plane andincluding an electrical tab extending laterally from an edge of a platein the cell in the x-direction to form an array of tabs extending alonga side face of the fuel cell stack in a z-direction orthogonal to thex-y plane, each tab being crimped to create a distortion in the tab outof the x-y plane of the plate; a connector device comprising a planarmember having a plurality of spaced-apart slits formed in the body ofthe planar member, each slit having an electrically conductive materialon an inside face of the slit; and the slits being spaced within theplanar member and configured to receive the tabs by sliding engagementin the x-direction so that each tab engages with at least a portion ofthe electrically conductive material on the inside face of a respectiveslit.

Each tab may be crimped to create a curved profile transverse to itslength. The curved profile may be a U-shaped profile or a V-shapedprofile viewed along the x-axis. The tabs may be each tapered at theirdistal ends such that the extent of out-of-plane distortion is reducedat the distal ends of the tabs. The array of tabs may comprise two rowsof tabs separated in the y-direction, the second row being offset fromthe first row in the z-direction so as to facilitate electricalconnection to a different set of plates in the stack than the first row.The planar member may be a printed circuit board with electricallyconductive tracks extending across the planar surface to theelectrically conductive material on the inside face of each slit.

In another aspect, there is an electrical connector device forconnecting to a plurality of cell voltage monitoring tabs in a fuel cellstack, in which the cell voltage monitoring tabs extend laterally froman edge of the fuel cell stack, the connector device comprising: aplanar member having a plurality of generally parallel slits formed inan edge of the planar member, each slit having an electricallyconductive material on an inside face of the slit; the slits beingspaced along the edge of the planar member and configured to receive thetabs by sliding engagement in the longitudinal direction of the slits;and each slit has a curved profile along its length.

In another aspect, there is a fuel cell stack comprising: a plurality offuel cells disposed in a stacked configuration, each cell substantiallyparallel to an x-y plane and including an electrical tab extendinglaterally from an edge of a plate in the cell in the x-direction to forman array of tabs extending along a side face of the fuel cell stack in az-direction orthogonal to the x-y plane; each tab including a hook atthe distal end of the tab, each hook extending in the y-direction.

In another aspect, there is a fuel cell stack comprising: a plurality offuel cells disposed in a stacked configuration, each cell substantiallyparallel to an x-y plane and including an electrical tab extendinglaterally from an edge of a plate in the cell in the x-direction to forman array of tabs extending along a side face of the fuel cell stack in az-direction orthogonal to the x-y plane, each tab being crimped tocreate a distortion in the tab out of the x-y plane of the plate tocreate a curved profile transverse to its length.

Exemplars are described by way of example and with reference to theaccompanying drawings.

DRAWINGS

FIG. 1 is a perspective view of a portion of a side face of a fuel cellstack with an array of cell voltage monitoring electrical connectiontabs extending out of the side face from each cell;

FIG. 2 is a perspective view of a connector device configured to matewith a row of connection tabs in the array of FIG. 1;

FIG. 3 is a perspective view of the portion of the side face of a fuelcell stack as shown in FIG. 1, further including a pair of connectordevices in which the upper connector device is positioned ready forengagement with an upper row of connection tabs and the lower connectordevice is coupled to the lower row of connection tabs;

FIG. 4 is a perspective view of the portion of the side face of a fuelcell stack as shown in FIGS. 1 and 3, further including a pair ofconnector devices coupled to the connection tabs;

FIG. 5 is a perspective view of an extended portion of the side face ofa fuel cell stack showing multiple connector devices coupled thereto anda further pair of connector devices in position ready for slidingconnection to the connection tabs;

FIG. 6 is a side elevation of the portion of side face of a fuel cellstack as shown in FIG. 3;

FIG. 7 is a perspective view of a portion of the side face of a fuelcell stack with an array of cell voltage monitoring electricalconnection tabs extending out of the side face from each cell and anumber connector devices coupled thereto; and

FIG. 8 is a perspective view of a connector device configured to matewith a row of connection tabs in the array of FIG. 7.

All callouts in the attached figures are hereby incorporated by thisreference as if fully set forth herein.

It should be appreciated that, for simplicity and clarity ofillustration, elements shown in the figures have not necessarily beendrawn to scale. For example, the dimensions of some of the elements areexaggerated, relative to each other, for clarity. Further, whereconsidered appropriate, reference numerals have been repeated among theFigures to indicate corresponding elements. While the specificationconcludes with claims defining the features of the present disclosurethat are regarded as novel, it is believed that the present disclosure'steachings will be better understood from a consideration of thefollowing description in conjunction with the figures, in which likereference numerals are carried forward. All descriptions and callouts inthe figures are hereby incorporated by this reference as if fully setforth herein.

Throughout the specification, the descriptors relating to relativeorientation and position, such as “top”, “bottom”, “left”, “right”,“up”, “down”, “front”, “back”, as well as any adjective and adverbderivatives thereof, are used in the sense of the orientation of fuelcell stack as presented in the drawings. However, such descriptors arenot intended to be in any way limiting to an intended use of thedescribed or claimed invention.

With reference to FIG. 1, a fuel cell stack includes a number of cells 1in a stacked configuration. Each cell 1 includes a number of componentssuch as a membrane-electrode assembly, electrode diffuser materials andsealing gaskets sandwiched between fluid flow plates as well known inthe art and not described further here. Each cell 1 is a generallyplanar structure occupying an x-y plane. As shown in FIG. 1, the x-axisextends into/out of the plane of the paper, while the y-axis extends inthe vertical direction. The z-axis extends left to right. However, nolimitation on the stack is implied by any particular choice oforientation of orthogonal x-y-z axes.

Each bipolar flow plate in the stack includes a cell voltage monitoringelectrical connection tab 2 extending in the x-direction from a sideface 3 of the stack. Each tab 2 emerges from an edge 4 of a respectivecell 1, e.g. through a pair of gasket seals (not shown). The pluralityof tabs 2 form an array, and in the embodiment shown the array is atwo-dimensional array in which a first row 5 of tabs 2 is separated inthe y-direction from a second row 6 of tabs 2. The second row 6 of tabs2 is also offset from the first row 5 of tabs 2 in the z-direction. Thisenables alternating ones of the bipolar plates in the stack to beconnected via cell voltage monitoring tabs 2 in each row 5, 6 of thearray, such that the density of tabs in the z-direction can besubstantially reduced, in this case by half.

It will be understood that the number of rows 5, 6 in the array of tabs2 can be one, two or more. The tabs 2 can be provided for every cell inthe stack or for less than every cell in the stack. The tabs 2 maycorrespond to each bipolar plate as described in this example, or ifseparate cathode flow plates and anode flow plates are used in thestack, the tabs 2 may be provided for one or both of each of the cathodeand anode flow plates.

Each tab 2 is preferably formed as an integral part of the plate, forexample pressed or stamped out of a sheet at the same time as the foilplate. Tabs 2 may be formed in multiple places on one or more edges ofthe plates.

As shown in FIG. 1, each tab 2 is preferably formed with a hook 8, 9 atthe distal end 7 of the tab 2 (the distal end being the end remote fromthe body of the plate). The hooks 8, 9 each extend in the y-direction,i.e. parallel with the side face 3 of the stack. The hooks 8 in thefirst row 5 preferably extend in the positive y-direction while thehooks 9 in the second row 6 extend in the opposite, i.e. negativey-direction, such that the hooks all face outwardly. Because ofmanufacturing tolerances, each plate in the stack, and therefore eachtab 2 in the array, may be shifted slightly from a precisely regulararray position, as shown exaggerated in the drawing. A typical scatterof components may arise from positional tolerances of ±0.2 mm. Thethickness of the tabs may be as low as 0.1 mm or thinner.

Referring to FIG. 2, a connector device 20 for coupling to the tabs 2 isnow described. The connector 20 has a generally planar member 21 whichmay be a printed circuit board or other suitable generally stiffmaterial. An edge 22 of the planar member 21 has a plurality of slits 23formed therein. The slits 23 preferably extend through the thickness ofthe planar member 21 to form a comb-like structure. The slits 23preferably have a width w which may taper out towards the open end 24 ofeach slit. A plurality of conductive tracks 25 are formed on a face ofthe planar member 21, each of which extends into a respective slit suchthat there is an electrically conductive material 26 on an inside faceof each slit 23.

Each slit preferably has a curved profile along its length, i.e. whenviewed along an axis orthogonal to the plane of the planar member.Preferably as shown in FIG. 2 the curved profile is in the form of ashallow ‘S’ shape extending along the longitudinal direction of the slit23. Each slit has an open end 29 and a closed end 19. Each slitpreferably has a bevel, chamfer or taper 18 at its open end 29 such thatthe slit widens at the open end. The expression ‘taper’ is intended toencompass both a bevelled end and a chamfered end. The taper may beprovided on one or both walls of the slit 23. The taper 18 is preferablyconfigured to widen the slit 23 at the open end 29 a sufficient amountso as to guide a tab 2 into the slit 23 taking into account themanufacturing tolerances of the stack, e.g. ±0.2 mm displacement of atab for a given tab thickness of, e.g. 0.1 mm. Thus, the slit 23 may bewidened at its open end 29 several fold. Those of ordinary skill in theart will recognize that the exact dimensions of the “S” shape within thefigures are not intended to be, nor should they be considered, alimitation on the scope of the disclosure.

Each connector 20 also includes a connector socket 27 mounted to theface of the planar member 21 with a plurality of electrical terminals 28for connection to a conventional external plug, such as that found on aconventional ribbon cable or similar. Each of the conductive tracks 25may be connected to a respective one of the electrical terminals 28.

Referring now to FIG. 3, the mating of the connector device 20 with anarray of tabs 2 is now described. FIG. 3 shows two connector devices 20,an upper connector 30 and a lower connector 31. The connector device 20is configured to present the planar member 21 to the side face 3 of thefuel cell stack such that the open ends 29 of each slit 23 present to arespective one of the tabs 2, as seen in the top portion of FIG. 3,indicated by upper connector 30. The upper connector 30 is thuspositioned ready for sliding engagement with the tabs 2 in they-direction, i.e. downwards. The thickness t of the planar member 21 ispreferably such that as the tabs 2 each slide into a respective slit 23,the hooks 8, 9 lie beyond the plane of the planar member 21 and, whenthe connector 20 is fully engaged, at least some hooks 8, 9 will hookover the planar member 21 at the closed end 19 of the slit, as mostclearly seen in the upper connector of FIG. 4. This assists inpreventing the connector from becoming detached from the tabs. The lowerconnector 31 of FIG. 3 is already engaged with its row of tabs 2 andalso shows this aspect. The length of the slits 23 is preferablyslightly longer than width of each tab (in the y-direction as seen inFIG. 1).

The taper 18 at the open end 29 of each slit 23 is configured to guideeach tab 2 for easy sliding engagement with the slit 23 notwithstandingpossible displacement of the tab from an exactly regular array position.Such departures from a strictly regular array can be a typical featureof normal manufacturing tolerances. The width w of the slits 23 (seeFIG. 2) is preferably selected to be wider than the thickness of thetabs, to ensure easy sliding engagement of the tabs 2 without unduefriction that could otherwise collapse or squash the tabs flat againstthe face of the fuel cell stack, given their thinness and therefore lowdegree of stiffness. The preferred curved shape of the slit 23 isselected so that good electrical contact of each tab 2 with theelectrically conductive material 26 on inside faces of the slits. As thetab 2 is gently forced to follow the curve of the slit, its surfaceswill engage with the slit in at least one or more places.

Although the preferred profile of slit 23 is an S-shaped curvetravelling along the plane of the planar member 21 (in the y-directionrelative to the fuel cell stack), other curved profiles of slit 23 maybe used that result in the creation of a minor distortion in the tab outof its x-y plane so as to ensure contact with the inside faces of theslit 23. For example, a simple shallow C-curve (one bend) rather thanthe two-bend S-curve could be used, or a three or more bend curve. Theslit may also be described as “serpentine” in profile along its length.The curved profile could alternatively or additionally be a curvaturetravelling through the plane of the planar member, i.e. the side wallsof the slits are not perpendicular to the plane of the planar member, ifthe planar member is made thick enough. Most generally, the curvedprofile of the slits is one which provides for minor distortion of a tab2 sufficient to ensure good contact with the sidewalls of the slit whileinsufficient to cause a collapse of the tab during sliding engagement.Those of ordinary skill in the art will recognize that the exactdimensions of the “C” or “S” shape within the figures are not intendedto be, nor should they be considered, a limitation on the scope of thedisclosure.

The minor distortion of the tabs that provides for good electricalconnection is preferably an elastic deformation so that operation of theconnector is reversible and re-engageable.

By providing a sliding engagement of the connector 20 with the tabs 2 inthe y-direction, rather than the conventional x-direction, thelikelihood of collapse of the tab is substantially reduced not leastbecause the early part of the engagement occurs towards the base 10 ofeach tab 2 rather than axially inwards from the distal end 7 of each tab2. The tapering 18 of the slits 23 also ensures that each tab 2 isproperly captured within a slit before any sliding engagement/distortionforce is generally applied by the first curved part of the slit, evenwhen some lateral displacement of the tab is required to overcomemanufacturing alignment tolerances discussed earlier.

FIG. 4 shows an upper connector 41 and a lower connector 40 both fullyengaged with a respect first row 5 and second row 6 of tabs 2.

FIG. 5 shows a number of connectors 50 a, 50 b, 50 c, 51 a, 51 b, 51 ccan be used to connect to long rows of tabs 2. Connecting to smallergroups of tabs 2 can be advantageous in avoiding problems withsignificant run-out in tab pitch over the length of a large fuel cellstack and reduces the risk of damage to individual tabs during connectorinsertion. In a preferred configuration, the connectors 50, 51 areformed such that a lateral edge 52 of a planar member 21 is shaped toform one half of a “slit” which will be completed when two adjacentconnectors 50 a, 50 b or 51 a, 51 b are connected to the tabs. Thus, theright hand edge 53 of connector 51 a forms the left side of a slit 55and the left hand edge 54 of connector 51 b forms the right side of theslit 55. The slit 55 is thus “created” when the second of an adjacentpair of connectors 51 a, 51 b are coupled to the tabs 2 by slidingengagement.

FIG. 6 shows a side elevation of the arrangement shown in figure inperspective view, more clearly showing upper and lower connectors 30,31, S-shaped slits 23 of width w, having tapers 18 at the open ends 24and also showing the closed ends 19. FIG. 6 also shows how selectedslits 60, 61 may be provided with a “barb” feature 62 configured tocapture a respective tab 63 once it is fully engaged in the slit 60, 61to thus enhance retention of the upper connector 30 on the tabs 2, 63.Lower connector 31 shows the tab 63 captive behind the barb 62. Torelease the upper and lower connector 30, 31 from the tabs 2, 63, thetwo end tabs 63 may be manually deflected to disengage the leading edgefrom the barb. Other forms of retention mechanism or retention membersmay be used instead of or as well as the barbs 62 in order to inhibitrelease of tabs from the connector in the y-direction.

For manufacturing convenience, each field plate could be formed with twoor more tabs extending from one edge, with one or more tabs beingremoved from each plate during assembly so that the remaining tab on aplate is positioned in the appropriate row 5 or 6 of the array of tabs.

An alternative configuration of tab and connector member is nowdescribed with reference to FIGS. 7 and 8. In this arrangement, bestseen in the left hand portion of FIG. 7, each tab 71 emerging from thestack side face 70 is crimped to create a distortion in the tab out ofthe x-y plane of the relevant plate. This crimp is preferably appliedduring pressing of the flow plate during manufacture of the flow plateand the corrugated flow channels therein, although it can be appliedseparately. The crimp preferably creates a curved or angled profiletransverse to the length of the tab (x-direction), and more preferablyin the shape of a shallow “U”-shape or shallow “V”-shape when the tab isviewed end on (i.e. when viewed along the x-axis in the drawing). Otherfeatures of the fuel cell stack forming the stack side face 70 may be asdescribed in connection with the arrangement of FIGS. 1 to 6.

Also as shown in FIG. 7, the tabs 71 preferably have tapered distal ends72, e.g. with bevelled or chamfered corners at the distal ends ratherthan square or rectangular distal ends. It will be understood thattapering the end of each tab 71 that is crimped into a U-shape orV-shape in the y-z plane has the effect of reducing the out-of-plane(x-y plane) distortion that exists at the distal ends of the tabs andthus reduces the initial resistance to insertion into a slit of aconnector as will now be described with reference to FIG. 8.

Each connector device 80 comprises a generally planar member 81 having aplurality of spaced-apart slits 82 formed in the body of the planarmember. Each slit 82 has an electrically conductive material 83 on aninside face of the slit. The slits 82 are spaced within the planarmember body to match arrays of tabs 74 on the fuel cell stack and arethereby configured to receive the tabs by sliding engagement in thex-direction so that each tab 71 engages with at least a portion of theelectrically conductive material 83 on the inside face of a respectiveslit.

The crimped profile of each tab 71 is arranged so that the height of the“U”-shape or “V” shape in the y-z plane is sufficient that each tab 71will be forced to distort or elastically deform somewhat in order tofully engage in the slit 82 thereby assuring good electrical contactwith the electrically conductive material 83. The tapered distal ends 72of the tabs 71 ensures that the tabs 71 can initially pass into theslits 82 with little or no resistance; it is only once the tabs havebeen guided part way into the slits 82 that the increasing z-profile ofthe tabs causes engagement with the walls of the slits. By that point,the tabs 71 are preferably sufficiently guided and captured by the slits82 that collapse or creasing of the tabs is unlikely, even if there issome alignment error in the positions of the tabs from a completelyregular array. FIG. 7 shows a number of connector devices 80 in engagedposition.

Each connector device 80 further includes a connector socket 87 mountedto the face of the planar member 81 with a plurality of electricalterminals 88 for connection to an external plug, such as that found on aconventional ribbon cable or similar. The electrically conductivematerial 83 located in each slit 82 is electrically connected to arespective terminal 88, for example by way of a conductive track formedon and extending across the surface of the planar member 81. As in theearlier described embodiments, the planar member may be a printedcircuit board (PCB) or other suitable generally stiff material.

In a preferred arrangement, the fuel cell stack provides an array oftabs 71 comprising two or more rows of tabs separated in they-direction. In the example shown in FIG. 7, there are four such rows 73a-73 d. Each of the successive rows is preferably offset from all of theother rows in the z-direction so as to facilitate electrical connectionto a different set of plates in the stack than any of the other rows.

The connectors described above in all embodiments are particularlysuitable as self-supporting, easily attached connectors that are robustand vibration-resistant while still taking into account the delicatenature of thin connector tabs. In the embodiments of FIGS. 1 to 6, thetapered nature of the slits and the angle of approach when the connectoris coupled to the tabs makes the connectors particularly suitable fortabs that have particularly large tolerances in position duringassembly, and can accept relatively large pitch variations. Similarly,the tapered nature of the tabs in the embodiments of FIGS. 7 and 8provides accommodation to large tolerances in tab position duringassembly, and can accept relatively large pitch variations.

The low insertion force required for engagement of the tabs makes theconnectors suitable for easy removal and reconnection without damage tothe tabs. The side entry of the connectors onto the tabs in theembodiments of FIGS. 1 to 6 means that they are advantageously compactand low profile. The connectors can readily be made modular in natureand the use of a PCB planar member makes the connectors low cost andeasily integrated with other components. The connector assembly can beused for both etched and pressed fuel cell field plates and separatorplates.

By using connectors that couple to many tabs at once, assembly costs canbe significantly reduced as can assembly errors. Risks of shortingbetween adjacent tabs may also be reduced and adjacent tab insulation isprovided by the structure of the PCB.

The slits in the PCB planar members can be formed by any suitableprocess, such as water, laser or die cutting. A preferred configurationof connector of the arrangements of FIGS. 1 to 6 has eleven slots butaccommodates twelve tabs by virtue of cooperation with an adjacentconnector as described earlier.

While the method and devices have been described in terms of what arepresently considered to be the most practical, it is to be understoodthat the disclosure need not be limited to the disclosedimplementations. It is intended to cover various modifications andsimilar arrangements included within the spirit and scope of the claims,the scope of which should be accorded the broadest interpretation so asto encompass all such modifications and similar structures. The presentdisclosure also includes any and all implementations of the followingclaims.

Further, each of the various elements of the disclosure and claims mayalso be achieved in a variety of manners. This disclosure should beunderstood to encompass each such variation, be it a variation of animplementation of any apparatus implementations, a method or processimplementations, or even merely a variation of any element of these.

Particularly, it should be understood that as the disclosure relates toelements of the invention, the words for each element may be expressedby equivalent apparatus terms or method terms—even if only the functionor result is the same.

Such equivalent, broader, or even more generic terms should beconsidered to be encompassed in the description of each element oraction. Such terms can be substituted where desired to make explicit theimplicitly broad coverage to which this invention is entitled.

It should be understood that all actions may be expressed as a means fortaking that action or as an element which causes that action.

Similarly, each physical element, disclosed, should be understood toencompass a disclosure of the action which that physical elementfacilitates. In this regard, it should be understood that, for practicalreasons, and so as to avoid adding potentially hundreds of claims, theapplicant has presented claims with initial dependencies only.

Any patents, publications, or other references, mentioned in thisapplication, for patent, are hereby incorporated by reference. Inaddition, as to each term used, it should be understood that, unless itsutilization in this application is inconsistent with suchinterpretation, common dictionary definitions should be understood, asincorporated, for each term, and all definitions, alternative terms, andsynonyms such as contained in at least one of a standard technicaldictionary recognized by artisans and the Random House Webster'sUnabridged Dictionary, latest edition, are hereby incorporated byreference.

Support should be understood to exist, to the degree required under newmatter laws, —including but not limited to United States Patent Law 35USC 132 or other such laws, —to permit the addition of any of thevarious dependencies or other elements presented under one independentclaim or concept as dependencies or elements under any other independentclaim or concept.

To the extent that insubstantial substitutes are made, to the extentthat the applicant did not in fact draft any claim so as to literallyencompass any particular exemplary implementations, and to the extentotherwise applicable, the applicant should not be understood to have inany way intended to or actually relinquished such coverage as theapplicant simply may not have been able to anticipate all eventualities;one skilled in the art, should not be reasonably expected to havedrafted a claim that would have literally encompassed such alternativeexemplary implementations.

Further, the use of the transitional phrase “comprising” is used tomaintain the “open-end” claims herein, according to traditional claiminterpretation. Thus, unless the context requires otherwise, it shouldbe understood that the term “comprise” or variations such as “comprises”or “comprising”, are intended to imply the inclusion of a stated elementor step or group of elements or steps but not the exclusion of any otherelement or step or group of elements or steps.

Such terms should be interpreted in their most expansive forms so as toafford the applicant the broadest coverage legally permissible.

The invention claimed is:
 1. A fuel cell stack assembly comprising: aplurality of fuel cells disposed in a stacked configuration to define afuel cell stack, each cell substantially parallel to an x-y plane andincluding an electrical tab extending laterally from an edge of a platein the cell in the x-direction to form an array of tabs extending alonga side face of the fuel cell stack in a z-direction orthogonal to thex-y plane, each tab being crimped to create a distortion in the tab outof the x-y plane of the plate; and a connector device comprising aplanar member having a plurality of spaced-apart slits formed in a bodyof the planar member, each slit having an electrically conductivematerial on an inside face of the slit, wherein the slits are spacedwithin the planar member and configured to receive the tabs by slidingengagement in the x-direction so that each tab engages with at least aportion of the electrically conductive material on the inside face of arespective slit, and wherein each tab has a length in the y-directionand is crimped to create one of a U-shaped profile and a V-shapedprofile viewed along the x-axis, and wherein the tabs are each taperedat their distal ends such that the extent of out-of-plane distortion isreduced at the distal ends of the tabs, each tab having beveled orchamfered corners at their distal ends.
 2. The fuel cell stack assemblyof claim 1, in which the distortion includes a curved or angled profilewhen viewed in the x-axis direction.
 3. The fuel cell stack assembly ofclaim 1 in which the planar member is a printed circuit board withelectrically conductive tracks extending across the body to theelectrically conductive material on the inside face of each slit.
 4. Thefuel cell stack assembly of claim 1, in which the slits and the tabs areconfigured to slidably engage in the x-direction via each tab engageswith at least a portion of the electrically conductive material on theinside face of a respective slit.
 5. The fuel cell stack assembly ofclaim 1 in which the array of tabs comprises a first row of tabs and asecond row of tabs, the first row and the second row being separated inthe y-direction, the second row being offset from the first row in thez-direction so as to facilitate electrical connection to a different setof plates in the stack than the first row.
 6. A method of assembling afuel cell stack assembly, the method comprising: disposing a pluralityof fuel cells disposed in a stacked configuration to define a fuel cellstack, each cell substantially parallel to an x-y plane and including anelectrical tab extending laterally from an edge of a plate in the cellin the x-direction to form an array of tabs extending along a side faceof the fuel cell stack in a z-direction orthogonal to the x-y plane,each tab being crimped to create a distortion in the tab out of the x-yplane of the plate to create a U-shaped profile or a V-shaped profilewhen viewed in the x-axis direction, each of the tabs the tabs beingtapered at their distal ends such that the extent of out-of-planedistortion is reduced at the distal ends of the tabs, each tab havingbeveled or chamfered corners at their distal ends; providing a connectordevice comprising a planar member having a plurality of spaced apartslits formed in the body of the planar member, each slit having anelectrically conductive material on an inside face of the slit, theslits being spaced within the planar member and configured to receivethe tabs; sliding the connector device relative to the tabs in thex-direction so that each tab engages with at least a portion of theelectrically conductive material on the inside face of a respectiveslit.